[MIPS] 64-bit Sibyte kernels need DMA32.

Sibyte SOCs only have 32-bit PCI.  Due to the sparse use of the address
space only the first 1GB of memory is mapped at physical addresses
below 1GB.  If a system has more than 1GB of memory 32-bit DMA will
not be able to reach all of it.

For now this patch is good enough to keep Sibyte users happy but it seems
eventually something like swiotlb will be needed for Sibyte.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/asm-mips/dma.h b/include/asm-mips/dma.h
index 833437d31ef1..d6a6c21f16db 100644
--- a/include/asm-mips/dma.h
+++ b/include/asm-mips/dma.h
@@ -92,6 +92,7 @@
 #define MAX_DMA_ADDRESS         (PAGE_OFFSET + 0x01000000)
 #endif
 #define MAX_DMA_PFN             PFN_DOWN(virt_to_phys((void *)MAX_DMA_ADDRESS))
+#define MAX_DMA32_PFN           (1UL << (32 - PAGE_SHIFT))
 
 /* 8237 DMA controllers */
 #define IO_DMA1_BASE    0x00    /* 8 bit slave DMA, channels 0..3 */